Working fluid for use in refrigerating systems and method of preventing corrosion in refrigerating systems



1952 G. F. ZELLHOEFER ETAL WORKING FLUID FOR USE IN REFRIGERATING SYSTEMS AND METHOD OF PREVENTING CORROSION IN REFRIGERATING SYSTEMS v Filed Jan. 10, 1948 O 0 m G O m w m 0 0 I- (DOOQOOOOOOOOQQOO INVENTORS 2227;4 7 7 v ,izlzeZZf/Kl gj FTTdF VEK Patented Jan. 15, 1952 UNITED 2,582,306 I C E WORKING FLUID FOR USE IN REFRIGERAT- ING SYSTEMS-AND M ING CORROSION SYSTEMS Glenn F. Zellhoefer,

Vickers, Chicago, Ill.

said Zellhoefer ETHOD OF PREVENT- IN REFRIGERATIN G Normal, and Samuel E. said Vickers assignor to Application January 10, 1948, Serial No. 1,607

'14 Claims. (01. 252-458) This invention relates to the art of refrigeration and in particular has reference to working fluids for use in refrigerating apparatus of the absorption type.

Such types of systems employ a working fluid consisting of a suitable absorbent and a suitable volatile refrigerant. Many combinationsof absorbents and refrigerants have heretofore been suggested. One particularly efficient working nuid is that disclosed in Zellhoefer Patent No. 2,149,947, issued March I, 1 939, for Refrigeration, and which working fluid consists of a -refrigerant comprising methylene chloride and an absorbent comprising a liquid di-substituted poly glycol derivative such as a diether thereof, and more particularly a dialkyl ether, such for example as tetraethylene glycol dimethyl ether. This latter substance may be properly described as dimethoxy-tetraethyleneglycol or dimethoxytetraglycol.

It has been found that working, fluids for absorption type refrigerating systems under some circumstances exert undesirable corrosiveaction upon the metals of which parts of the system are constructed, particularly such parts made of iron and steel. Corrosion has been found in such systems even though the system and the working fluid originally were not contaminated and the refrigerant for the system was carefully prepared and was initially substantially free of acid-reacting materials, and even in cases where the absorbent was itself non-corrosive, yet during the operation of the system corrosion of metal parts of the system, particularly ferrous metal parts, has sometimes occurred. I

The corrosive difliculty is believed to be due to the presence in the working fluid of certain orv ganic and inorganic -materials, the precise natures of which have not been determined, but which appear to .be principally chlorides developed by the decomposition of the chlorine-containing constituents of the working fluid.

As disclosed in the aforesaid patent, the chlorine compounds of the general type exemplified by those containing the dichloromethyl group or ties heretofore encountered with such working fluids can be substantially eliminated and the working fluid stabilized by using with such working fluid copper and/ or cuprous oxide, preferably in a finely divided state. The invention thus contemplates a non-corrosive, stabilized working fluid consisting of suitable combinations of ab serpents and refrigerants of the types previously mentioned containing copper and/or cuprous oxide, preferably in a finely divided state. The invention also contemplates a technique for eliminating corrosion in refrigerating systems using such working fluids by adding to the fluid in the system copper and/or cuprous oxide, preferably in a finely divided state, or replacement of the contaminated working fluid in the system by a non corrosive mixture including copper and/or cuprous oxide, preferably in a finely divided state.

A. principal object of the invention, therefore, is to provide a non-corrosive, stabilized working fluid useful in a refrigerating system, particularly one of the absorption type.

Another object of the invention is to provide a technique for eliminating" and/or preventing corrosion in a system in which corrosion has already occurred by the use of a working fluid of the type previously discussed containing copper and/or cuprous oxide, preferably in a finely divided state.

Other. objects and advantages of the invention will be apparent from a consideration of the following specification taken in conjunction with the accompanying drawing, of which there is one sheet and wherein:

The sole figure is a schematic drawing of a refrigerating sy'stemof the type in which a workradical (-CHC12). are capable of formingv a thermally unstable loose molecular type of com-. pound with the glycol ether absorbents, and for such reasons are considered to be desirable as aworking fluid for an absorption system.

Of these glycol ethers, the following are considered as being within the scope of the present invention, to-wit: Diethylene glycol diethylether, triethylene glycol dimethylether, tetraethylene glycol dimethylether, pentaethylene glycol di- "methylether, hexaethylene glycol dimethylether,

diethylene glycol ditetrahydrofurfuryl ether,

ethylene glycol mono-n-butyl mono-tetrahydroviurfuryl ether, and the like. cover the above materials by the term glycol Tether in the subjoined claims.

It is intended to We have discovered that the corrosion difiicuL ing,..fluid embodying .the invention may be employed.

U As illustrated in the drawing, an absorption type refrigerating system in which working fluid embodying the invention may be employed consists in general of an absorber H], a heat exchanger I 2, a solution pump and motor assembly -l4,aheater or still IS, a condenser l8, and a watei'ichiller or cooler 20. When the solution pump l4 operates, strongsolution from the ab- H sorberlll flows through the outer passages of the heatexchanger l2 to the heater I6 through the conduit 22. Steam for operating the heater is supplied through the conduit 24. In the heater the solution absorbs heat from the steam, causing the distillation of the major portion of the refrigerant from the solvent. The refrigerant vapor released in the heater flows to the condenser l8 through the conduit 26. Water is supplied to oooling'conduits 28 in the condenser l8 through the conduits 30 for condensing there frigerant in the condenser l8, and the water is carried away from the condenser I8 by conduit 32. Liquid refrigerant flows from the condenser through conduit 34 and dehydrator 36 and cona duit 38. to the water chiller, .12; float. controlled valve lllmetering the. flow of Ltheliquidrefrigerant into the chiller 20 in accordance with the liquid level therein.

Water to be cooled flowsiinto thezcoiisflof the heat exchanger in the chiller 20 through'conduit M, and heat absorbed by the liquidrefrigerant in the chiller 20 causes such refrigerant to vaporize under the low pressure inthechiller, and the refrigerant vapor then flows throughrconduit 46 to the absorber lb. The water after being cooled in the heat exchanger 42,.is conducted away from the chiller through conduit 48.

While the refrigerant is following the'foregoing cycle from the heater to the absorber, the weak solution in the heater flows through the conduit 50, the inner-passages of the heat. exchanger l2, and the'conduit 52 to the absorber l0, and such solution is discharged through nozzles d under a pressure differential of the order of 3 to 4 poundsin theform-of a flne spray which impinges upon 'the'absorber coil 56'and then flows downwardly over the fins of'the coil in a thin film, absorbing theirefrigerantvapor that enters the absorber through the conduit 45.

The coil 56 is supplied with'water'fiw'whereby to absorb heat from the absorber,'and the'water after flowing through the coil 56may baconducted by conduit 30 toJthe heat'absorbing'coil 28 in the condenser. 'The strong solution formed in the absorber by the absorption-of the refrigerant vapor by the weak solution flowsbygravity to the suction side of'the solution'pump' Wand is thereby returned through .the conduit 22'to' the heater previouslyidescribed.

.The foregoing cycles of the refrigerantand'the solution continue as long as thepump Mremains in operation, thereby continuously absorbing heat from the current of water in 'the chiller "20. When the solutionpump l4 isstopped, the solutionfrom the heater l6 flows intothe absorber H) and an equilibrium is established between the highand low sides. of the system. Upon' starting the pump operation'again, the discharge of the strongsolution into .the heater will generate .the necessary head pressures to efiectthecirculation of the weak solution fromtheiheater to the absorber.

'As previously"indicated, it has. sometimes" been it was found that the corrosion difficulties could ibe.substantially eliminated by .adding to such working fluid mixture from .1% to 5% by weight It has also been found that cuprous'oxide, preferably in a finely divided state, to a Working solution mixture in a machine in whichcorrosionhasoccurred will not only preventfurther-corrosion, but will also convert the working solution mixture into a non-corrosive.

"stabilized'workingtfluid. The corrosion has been found touoccur principally in the ferrous metal parts of the system exposed to high temperatures. such for instance as the heater which is subjected to the steam temperature of the order of 240.Fxarid the 'heat'exchanger i2 through which the'hotweak liquor is returned to the absorber.

..It. has also been found that such addition of su'chzan amount of. copper and/or cuprous oxide, preferablyin a finely divided state, will thermally andqotherwise'stabilize the solution against deterioration. Table I, hereinafter'set forth, is a comparison of "thesresults obtained by a number of .testsmade of working mixtures in the presence of.a standard steel-copper couple,.some with and: some withoutv copper or cuprous oxide inafinelyidivided state,.in a glass bomb. The standard couple used in alltests herein'referred to is acoldrrolledisteel'rod.i" long, diameter, around which is wrapped a copper'wire .040 in. diameter,'?3"long. The original acidity of the freshly prepared mixtures in test'No. 56194-4 was 015% or less calculated as HCl which is commercially. satisfactory and substantially free of acid.:reacting.materials from a commercial standpoint. The-deteriorated solutions referred to inthetests are a composite of. sample solutions taken frame. number of machines after considerable .use .in :actual service, 1 and analysis after makeup ofuthese solutions'indicated that they contained:objectionablesamounts of iron chlo ride, iron oxide,'-'HCl and iron organic complexes. These-deteriorated solutions originally when intrdduced in" the machineswere 1 substantially free ofacid'reacting materials and the systems of the machines in "which .such original solutions were originally introduced werenot contaminated.

.. Table I Table showing silectivenossoficopper or cuprousnxide-forstabiliZingwnrkingruixtures and suppressing cor rosrvenessof.dunetho}!ytetreglynolinethylenechloride solutioni presence of standard steel-copper couple] Tim "'1: Murray 01 I W of id I e; omp., r-ss. .er on, 111 Y .0. Test No. Content of Glass Bomb days Cent Pet Cent Qoupsle, Couma HG] gm Per Cent 1619.44 80% solvenh-"m liefrlgeraut- *I 3 I25 0'; 0.55 2. 3590 -2. 52

: Standard. Gouple. 5636.1..- .Deteriorated solution with acid-. 18 $125 0. 59 0. 54 2. 4350 2. 66

- ty 0.13%calc. as HCl i'tand zard couple. v 5537.1-1 'SDeterioratcd solution with acid: '"3 .125 0206 .0. 08 2. 4991 +0.192

Y ity 0.18% calcs as 'HGI Cn- I 1 Standard Couple. I g J5637.3-'2. -M. Detcrloratcd solution with acid- 125 0104 0107 2. 4542 +0. 465 lty"0.13%0310.ES HCI-CLfiO StandardCouple.

gradual deterioration in'the efiiciencyof theamachine. resulting in an eventual ibreakdown ethereof.v The solution-may. comprise; from .40+90'% -.by weightof solventrend from;10+60%%1by:sveight:of refrigerant.

:Forssatisfactory.commercial operation of re-- frigeratingz machines of the foregoing type, the acidity .of. the working fluid must be maintained .atorzbelow aper-centagezof .015% determined as some "with aand 'rsome without copper and/or HCl.

'Ifable II,:hereinaftersset-forth;.is a comparison ofxther-esults-obtained .byav number of tests made of workingmixtures .in :copper and steel bombs,

Afteran extensive period. of research. and tests 5 s cuprous oxide in a finely dividedstate.

abaasoe [Table showing effectiveness of copper and/or cuprous oxide for stabilizing working mixtures and suppressing corrosivenoss of (1imetlioxytetra-glycol-methylene chloride solutions in both comic" and steel bombs] I v Acidity of Acidity of la 9 Solution Solution T t 3: Cale. as Cale. as Content of Bomb u 10 Per Cent Per Cent No. Cale as H H After Alter 4 days 8 days 925-1 80% Solvent, 20% Reirigerant in copper bomb. 0. 00936 0.0051 0. 0072 025-2 80% Solvent, 20% Reirigerant in Cu bomb with finely divided Cu powder 0. 00936 0.0072 0. 0079 925-3 80% Solvent, 20% Reirigerant in Cu bomb with finely divided Cu and C1120 Powder 0.00936 0.0072 0.0072 0254 80% Solvent, 20% Refrigerant in steel bomb with Cu powder (finely di- Vide 0. 00936 0.00612 0. 00756 095 80% Solvent, 20% Reirigerant in steel bomb with C1120 (finely divided) 0. 00036 0. 00048 0. 00792 0254) 80% Solvent, 20% Reirigerant in steel bomb with V finely divided Cu and C1120 l 0. 00936 0. 0072 0. 0090 Table III [This table shows the effectiveness of powdered copper, finely divided cupi'ous oxide, mixture of powdered copper and finely divided cuprous oxide and copper tubing in adsorbing products of corrosion from a composite sample of deteriorated solutions 'taken from machines in the field] Original Acidity Acidity SAohgiton P as 1 P aCs t .ci i y er en er en:

Test No. HOP

Per Cent After 24 A fter 72 H01 hours hours Cu., 200 F., #923-1 a. 0.1530 0.0072 0.0054 C11, 200 F., #923-2. 0. 1530 0.0126 0. 0072 Cu, 90 F., #9233- 0. 1530 0. 0108 0. 0030 CuzCl, 200 F., #923-4 0.1530 0.0108 0. 0108 CuzO, 200 F., #923-5 0.1530 0.0117 0.0108 Cu2O, 90 F., #923-6 0.1530 0.0126 0.0108 GU20, Cu, 200 F #923-7 0.1530 0.0099 0.0072 C1120, (u, 200 F #923-8 0.1530 0. 0099 0.0072 C1120, Cu, 90 F #923-9. 0,1530 0. 0135 0. 0090 On Bomb} 200 F #923-1 0.1530 0.0252 0. 0252 Cu B0nib, 90 F., #923-11 0. 1530 0. 0270 0.0270

1 Cu indicates tests in copper bombs with gm. of precipitated copper powder in 70 cc. of solution, Cu2Oind1cates tests in copper bombs with 5 gm. of finely divided cuprous oxide in cc. of solution,

CugO-Cu indicates tests in copper bombs with 2.5 gm. precipitated copper powder and 2.5 gm. finely divided cuprous oxide in 70 cc. of solution, and Cu Bomb indicates tests in copper bomb with 70 cc. of solution and no GU20 or Cu in addition to that of the walls of the bomb.

Table IV From the foregoing tests and from tests made in systems of machines in actual service it has been definitely established that the addition of copper and/or cuprous oxide in the amounts in dicated and preferably in a finely divided form will stabilize such working fluids against deterioration and will render such working fluids non' corrosive to the metal parts of such systems.

While we have illustrated and described a pre ferred embodiment of our invention, it is understood that this is capable of modification, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.

We claim:

1. A stabilized working fluid for use in a refrigeration system of the absorption type consisting of a mixture of the following ingredients: 40% to of a glycol other, .1% to 5% of copper and. 10% to 60% of a highlyvolatile aliphatic halide containing at least one hydrogen atom.

2. A stabilized working fluid for use in a refrigeration system of the absorption type consisting of a mixture of the following ingredients: 40% to 90% of a glycol ether, .1% to 5% of cuprous oxide and 10% to 60% of a highly volatile aliphatic halide containing at least one hydrogen atom.

3. A stabilized working fluid for use in a refrigeration system of the absorption type consisting of a mixture of the following ingredients: 401% to 90% of a glycol ether, .l% to 5% of copper and cuprous oxide in a finely divided form, and 10% to 60% of a highly volatile aliphatic halide containing at least one hydrogen atom.

4. In a refrigerating system of the absorption type employing a volatile organic halide as the refrigerant and a glycol ether as the absorbent, the process of preventing corrosion of the ferrous metal portions of the system by such fluids and stabilizing the mixture of such fluids which comprises using with the refrigerant and ab sorbent mixture, .1% to 5% of copper in a finely divided form.

5. In a refrigerating system of the absorption type employing a volatile organic halide as the refrigerant and a glycol ether as the absorbent, the process of preventing corrosion of the ferrous metal portions of the system by such fluids and stabilizing the mixture of such fluids which comprises using with the refrigerant and absorb- [This table shows selective adsorption properties of powdered copper and cuprous oxide for six different acids in three different solvents] Solvent, 50 Gram Acid Inhibitor GuzO (5 gram). do

pppppppppppppppppp o onolam 999999999999999999 0 one can: 0

7 ent-mixture..l% to 5% ..:of tcuprous oxidein a finely; dividedform.

'6...'.I n. a. refrigerating system of the -.absorption type. employing a vvolatile..organic.halide as the refrigerant. and .a ,glycol ether ..as the absorbent, the; process ofgpreventingcorrosion of the ferrous metal portions .of the system .by such fluids and stabilizing themixtureof. suchffiuids which comprises using with therefrigerant.andabsorbent mixture, .1% .to 5% of .copperlandcuprousoxide in a finely dividediform.

'7. Amixturesuitable iormse asa working fluid fora. refrigerating .systemoi the absorption type consisting ofirom A0 .toTQOpercent by weight of dime'thoxy=tetraethyleneglycol vvand .from 10 to 60 per cent by weight of methylene chloride, andoiirom .Lto -5 percent by weight of copper in .a finely divided. form.

.8.. A mixture. suitable for vuseas a workiiigrluicl forarefrigerating system of .the absorption type consisting ofiromAOtoQO per cent by weight of dimethoxy-tetraethyleneglycol.and from it to 60..per.cent.by weightoi methylenechloride, and of..from.'.1.to. 5,.pe1xcentby weight er cuprous oxide in a finely. divided. form.

.9.v A mixture suitable foruse. as a working 'iiuid for: refrigerating. system of the. absorption type consistingof "from A0 toJJQO peizcent .by weight of dimethoxytetraethyleneglycol and ,fromJO to $0 percentby weightotmethylenechloride, and of. from. .1 to. 5 .pencent'loy weight. of copper. and cuprousoxide in afinely dividedform.

.10. :A mixture .of .r'dime'thoxy tetraethylenegl 001 and methylenechloride containing il%..to'5% by weightof .material .from the group consisting-of copper and cuprous oxide.

-11...A stabilized working fiuidlfor use in a refrigerating-system of the-absorptiontype con- .1% GO-5% ofcopper.

slsting or a. mixturewtaaa-glycol ether, a highly volatile aliphatic halide containing at least one hydrogen'atonrandJ' qb to 5'5 .by 'weight'ot material selected from the group "consisting of copper and cuprous oxide.

12. A working fluid for use in a refrigerating systemofrthesabsorption type consisting of 'a glycol-ether and a highly volatile aliphatic halide containing at leastone hydrogen atom stabilized and made non-corrosive to ferrous metals by the presence or .1% to 5% by weight of material selected from the group consisting of copper and cuprous oxide in afinely divided form.

13. A method of preventing corrosion of ferrous metals by and stabilizing a mixture of dimethoxy tetraethyleneglycol and a methylene chloride which comprisesusing with'such mixture, .I% to.5% .by weight of material selected from the group "consisting .of .copperand cuprous oxide.

14. Amethod-of preventing corrosion of ferrous metals by and stabilizing a mixture of dimethoxy-etetraethyleneglycol and a methylene chloride which: comprises'adding to such mixture,

GLENN F. ZELLHOEFER. 'SAMUEL'E. VICKERS.

REFERENCES 'CITED The-following.references are of record in the 'file :df this zpatent:

UNITED STATES PATENTS Number Name Date 1,986,973 'Hetherington et al. Jan. 8, 1935 "2,149,947 Zellhoefer .Mar. 7, 1939 2,246,665 Buflington June 24, 1941 

1. A STABILIZED WORKING FLUID FOR USE IN A REFRIGERATION SYSTEM OF THE ABSORPTION TYPE CONSISTING OF A MIXTURE OF THE FOLLOWING INGREDIENTS: 40% TO 90% OF A GLYCOL ETHER, 1% TO 5% OF COPPER AND 10% TO 60% OF A HIGHLY VOLATILE ALIPHATIC HALIDE CONTAINING AT LEAST ONE HYDROGEN ATOM. 